DESCRIPTION: The application has three overall goals; first, the mechanism of mating type switching in baker's yeast will be examined, and in particular the molecular basis of donor preference, second, the molecular details of double strand break (DSB) induced recombination will be studied and third, the role of genes in replication, repair and recombination in DSB-induced recombination will be examined. Also the effect of chromatin on mating type switching and other DSB-induced events will be studied.